Abstract
The size of human brain tripled over a period of approximately 2 million years (MY) that ended 0.2-0.4 MY ago. This evolutionary expansion is believed to be important to the emergence of human language and other high-order cognitive functions, yet its genetic basis remains unknown. An evolutionary analysis of genes controlling brain development may shed light on it. ASPM (abnormal spindle-like microcephaly associated) is one of such genes, as nonsense mutations lead to primary microcephaly, a human disease characterized by a 70% reduction in brain size. Here I provide evidence suggesting that human ASPM went through an episode of accelerated sequence evolution by positive Darwinian selection after the split of humans and chimpanzees but before the separation of modern non-Africans from Africans. Because positive selection acts on a gene only when the gene function is altered and the organismal fitness is increased, my results suggest that adaptive functional modifications occurred in human ASPM and that it may be a major genetic component underlying the evolution of the human brain.
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- Bond Jacquelyn, Roberts Emma, Mochida Ganesh H., Hampshire Daniel J., Scott Sheila, Askham Jonathan M., Springell Kelly, Mahadevan Meera, Crow Yanick J., Markham Alexander F. ASPM is a major determinant of cerebral cortical size. Nat Genet. 2002 Sep 23;32(2):316–320. doi: 10.1038/ng995. [DOI] [PubMed] [Google Scholar]
- Britten Roy J. Divergence between samples of chimpanzee and human DNA sequences is 5%, counting indels. Proc Natl Acad Sci U S A. 2002 Oct 4;99(21):13633–13635. doi: 10.1073/pnas.172510699. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Brunet Michel, Guy Franck, Pilbeam David, Mackaye Hassane Taisso, Likius Andossa, Ahounta Djimdoumalbaye, Beauvilain Alain, Blondel Cécile, Bocherens Hervé, Boisserie Jean-Renaud. A new hominid from the Upper Miocene of Chad, Central Africa. Nature. 2002 Jul 11;418(6894):145–151. doi: 10.1038/nature00879. [DOI] [PubMed] [Google Scholar]
- Cavalli-Sforza L. Luca, Feldman Marcus W. The application of molecular genetic approaches to the study of human evolution. Nat Genet. 2003 Mar;33 (Suppl):266–275. doi: 10.1038/ng1113. [DOI] [PubMed] [Google Scholar]
- Chen F. C., Li W. H. Genomic divergences between humans and other hominoids and the effective population size of the common ancestor of humans and chimpanzees. Am J Hum Genet. 2001 Jan 15;68(2):444–456. doi: 10.1086/318206. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Enard Wolfgang, Przeworski Molly, Fisher Simon E., Lai Cecilia S. L., Wiebe Victor, Kitano Takashi, Monaco Anthony P., Päbo Svante. Molecular evolution of FOXP2, a gene involved in speech and language. Nature. 2002 Aug 14;418(6900):869–872. doi: 10.1038/nature01025. [DOI] [PubMed] [Google Scholar]
- Eyre-Walker Adam. Changing effective population size and the McDonald-Kreitman test. Genetics. 2002 Dec;162(4):2017–2024. doi: 10.1093/genetics/162.4.2017. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fay J. C., Wu C. I. Hitchhiking under positive Darwinian selection. Genetics. 2000 Jul;155(3):1405–1413. doi: 10.1093/genetics/155.3.1405. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fay J. C., Wyckoff G. J., Wu C. I. Positive and negative selection on the human genome. Genetics. 2001 Jul;158(3):1227–1234. doi: 10.1093/genetics/158.3.1227. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fay Justin C., Wyckoff Gerald J., Wu Chung-I. Testing the neutral theory of molecular evolution with genomic data from Drosophila. Nature. 2002 Feb 28;415(6875):1024–1026. doi: 10.1038/4151024a. [DOI] [PubMed] [Google Scholar]
- Fu Y. X., Li W. H. Statistical tests of neutrality of mutations. Genetics. 1993 Mar;133(3):693–709. doi: 10.1093/genetics/133.3.693. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Gonzalez C., Saunders R. D., Casal J., Molina I., Carmena M., Ripoll P., Glover D. M. Mutations at the asp locus of Drosophila lead to multiple free centrosomes in syncytial embryos, but restrict centrosome duplication in larval neuroblasts. J Cell Sci. 1990 Aug;96(Pt 4):605–616. doi: 10.1242/jcs.96.4.605. [DOI] [PubMed] [Google Scholar]
- Harpending H. C., Batzer M. A., Gurven M., Jorde L. B., Rogers A. R., Sherry S. T. Genetic traces of ancient demography. Proc Natl Acad Sci U S A. 1998 Feb 17;95(4):1961–1967. doi: 10.1073/pnas.95.4.1961. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kaessmann H., Wiebe V., Weiss G., Päbo S. Great ape DNA sequences reveal a reduced diversity and an expansion in humans. Nat Genet. 2001 Feb;27(2):155–156. doi: 10.1038/84773. [DOI] [PubMed] [Google Scholar]
- Kimura M. A simple method for estimating evolutionary rates of base substitutions through comparative studies of nucleotide sequences. J Mol Evol. 1980 Dec;16(2):111–120. doi: 10.1007/BF01731581. [DOI] [PubMed] [Google Scholar]
- Kong Augustine, Gudbjartsson Daniel F., Sainz Jesus, Jonsdottir Gudrun M., Gudjonsson Sigurjon A., Richardsson Bjorgvin, Sigurdardottir Sigrun, Barnard John, Hallbeck Bjorn, Masson Gisli. A high-resolution recombination map of the human genome. Nat Genet. 2002 Jun 10;31(3):241–247. doi: 10.1038/ng917. [DOI] [PubMed] [Google Scholar]
- Kumar Arun, Markandaya M., Girimaji S. C. Primary microcephaly: microcephalin and ASPM determine the size of the human brain. J Biosci. 2002 Dec;27(7):629–632. doi: 10.1007/BF02708369. [DOI] [PubMed] [Google Scholar]
- McDonald J. H., Kreitman M. Adaptive protein evolution at the Adh locus in Drosophila. Nature. 1991 Jun 20;351(6328):652–654. doi: 10.1038/351652a0. [DOI] [PubMed] [Google Scholar]
- McHenry H. M. Tempo and mode in human evolution. Proc Natl Acad Sci U S A. 1994 Jul 19;91(15):6780–6786. doi: 10.1073/pnas.91.15.6780. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Murphy W. J., Eizirik E., O'Brien S. J., Madsen O., Scally M., Douady C. J., Teeling E., Ryder O. A., Stanhope M. J., de Jong W. W. Resolution of the early placental mammal radiation using Bayesian phylogenetics. Science. 2001 Dec 14;294(5550):2348–2351. doi: 10.1126/science.1067179. [DOI] [PubMed] [Google Scholar]
- Ptak Susan E., Przeworski Molly. Evidence for population growth in humans is confounded by fine-scale population structure. Trends Genet. 2002 Nov;18(11):559–563. doi: 10.1016/s0168-9525(02)02781-6. [DOI] [PubMed] [Google Scholar]
- Rozas J., Rozas R. DnaSP version 3: an integrated program for molecular population genetics and molecular evolution analysis. Bioinformatics. 1999 Feb;15(2):174–175. doi: 10.1093/bioinformatics/15.2.174. [DOI] [PubMed] [Google Scholar]
- Satta Y., Klein J., Takahata N. DNA archives and our nearest relative: the trichotomy problem revisited. Mol Phylogenet Evol. 2000 Feb;14(2):259–275. doi: 10.1006/mpev.2000.0704. [DOI] [PubMed] [Google Scholar]
- Smith Nick G. C., Eyre-Walker Adam. Adaptive protein evolution in Drosophila. Nature. 2002 Feb 28;415(6875):1022–1024. doi: 10.1038/4151022a. [DOI] [PubMed] [Google Scholar]
- Tajima F. Statistical method for testing the neutral mutation hypothesis by DNA polymorphism. Genetics. 1989 Nov;123(3):585–595. doi: 10.1093/genetics/123.3.585. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Takahata N., Satta Y., Klein J. Divergence time and population size in the lineage leading to modern humans. Theor Popul Biol. 1995 Oct;48(2):198–221. doi: 10.1006/tpbi.1995.1026. [DOI] [PubMed] [Google Scholar]
- Wakefield J. G., Bonaccorsi S., Gatti M. The drosophila protein asp is involved in microtubule organization during spindle formation and cytokinesis. J Cell Biol. 2001 May 14;153(4):637–648. doi: 10.1083/jcb.153.4.637. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Yang Z. PAML: a program package for phylogenetic analysis by maximum likelihood. Comput Appl Biosci. 1997 Oct;13(5):555–556. doi: 10.1093/bioinformatics/13.5.555. [DOI] [PubMed] [Google Scholar]
- Zhang J., Kumar S., Nei M. Small-sample tests of episodic adaptive evolution: a case study of primate lysozymes. Mol Biol Evol. 1997 Dec;14(12):1335–1338. doi: 10.1093/oxfordjournals.molbev.a025743. [DOI] [PubMed] [Google Scholar]
- Zhang J., Nei M. Accuracies of ancestral amino acid sequences inferred by the parsimony, likelihood, and distance methods. J Mol Evol. 1997;44 (Suppl 1):S139–S146. doi: 10.1007/pl00000067. [DOI] [PubMed] [Google Scholar]
- Zhang J., Rosenberg H. F., Nei M. Positive Darwinian selection after gene duplication in primate ribonuclease genes. Proc Natl Acad Sci U S A. 1998 Mar 31;95(7):3708–3713. doi: 10.1073/pnas.95.7.3708. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Zhang Jianzhi, Webb David M. Evolutionary deterioration of the vomeronasal pheromone transduction pathway in catarrhine primates. Proc Natl Acad Sci U S A. 2003 Jun 25;100(14):8337–8341. doi: 10.1073/pnas.1331721100. [DOI] [PMC free article] [PubMed] [Google Scholar]